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Multipartite entanglement has been widely regarded as key resources in distributed quantum computing, for instance, multi-party cryptography, measurement based quantum computing, quantum algorithms. It also plays a fundamental role in…

Quantum Physics · Physics 2020-09-23 Nengkun Yu

We establish a necessary and sufficient condition for the existence of a quantum state that reproduces given correlation values in the Clauser--Horne--Shimony--Holt (CHSH) setup for any fixed normalized observables. This result addresses a…

Quantum Physics · Physics 2025-06-17 Ryosuke Nogami , Jaeha Lee

The determination of the state fidelity and the detection of entanglement are fundamental problems in quantum information experiments. We investigate how these goals can be achieved with a minimal effort. We show that the fidelity of GHZ…

Quantum Physics · Physics 2008-09-27 Otfried Gühne , Chao-Yang Lu , Wei-Bo Gao , Jian-Wei Pan

We use hyper-entanglement to experimentally realize deterministic entanglement swapping based on quantum Elegant Joint Measurements. These are joint projections of two qubits onto highly symmetric, iso-entangled, bases. We report…

Quantum networks promise an unprecedented leap in semi-device-independent communication and security by capitalizing on quantum steering. However, current methods for assessing quantum network steering are constrained to specific cases. In…

Quantum Physics · Physics 2025-01-30 Ming-Xiao Li , Yuqi Li , Ya Xi , Chang-Yue Zhang , Ying-Zheng Wang , Rui-Bin Xu , Shao-Ming Fei , Zhu-Jun Zheng

Detection and quantification of entanglement in quantum resources are two key steps in the implementation of various quantum-information processing tasks. Here, we show that Bell-type inequalities are not only useful in verifying the…

Quantum Physics · Physics 2011-02-28 Yeong-Cherng Liang , Tamas Vertesi , Nicolas Brunner

Certifying quantum properties from the probability distributions they induce is an important task for several purposes. While this framework has been largely explored and used for quantum states, its extrapolation to the level of channels…

Quantum Physics · Physics 2025-07-23 Albert Rico , Moisés Bermejo Morán , Fereshte Shahbeigi , Karol Życzkowski

Instantaneous measurements of non-local observables between space-like separated regions can be performed without violating causality. This feat relies on the use of entanglement. Here we propose novel protocols for this task and the…

Quantum Physics · Physics 2015-05-20 Salman Beigi , Robert Koenig

The multipartite nonlocality provides deep insights into the fundamental feature of quantum mechanics and guarantees different degrees of cryptography security for potential applications in the quantum internet. Verifying multipartite…

Quantum Physics · Physics 2024-06-24 Ming-Xing Luo , Shao-Ming Fei

Entanglement detection is a fundamental task in quantum information science, serving as a cornerstone for quantum benchmarking and foundational studies. With an increasing qubit number that can be effectively controlled, there is a pressing…

In the last decade, it was understood that quantum networks involving several independent sources of entanglement which are distributed and measured by several parties allowed for completely novel forms of nonclassical quantum correlations,…

To date, most efforts to demonstrate quantum nonlocality have concentrated on systems of two (or very few) particles. It is however difficult in many experiments to address individual particles, making it hard to highlight the presence of…

Entanglement serves as a fundamental resource for various quantum information processing tasks. Fidelity of entanglement (which measures the proximity to a maximally entangled state) and various quantum entropies are key indicators for…

Quantum Physics · Physics 2025-10-21 Komal Kumar , Bivas Mallick , Tapaswini Patro , Nirman Ganguly

Entanglement of high-dimensional and multipartite quantum systems offer promising perspectives in quantum information processing. However, the characterization and measure of such kind of entanglement is of great challenge. Here we consider…

Quantum Physics · Physics 2020-03-20 Ming Li , Huihui Qin , Chengjie Zhang , Shuqian Shen , Shao-Ming Fei , Heng Fan

High-dimensional entanglement offers significant advantages over low-dimensional ones in various information-processing tasks. However, to harness these advantages, it is crucial that the quantum channels used to store or transmit the…

Quantum Physics · Physics 2025-12-25 Saheli Mukherjee , Bivas Mallick , Pratik Ghosal

We investigate the complexity cost of demonstrating the key types of nonclassical correlations --- Bell inequality violation, EPR-steering, and entanglement --- with independent agents, theoretically and in a photonic experiment. We show…

Entanglement depth quantifies how many qubits share genuine multipartite entanglement, but certification typically relies on tailored witnesses or full tomography, both of which scale poorly with system size. We recast entanglement-depth…

Quantum Physics · Physics 2025-12-16 Marcin Płodzień

We have applied an entanglement purification protocol to produce a single entangled pair of photons capable of violating a CHSH Bell inequality from two pairs that individually could not. The initial poorly-entangled photons were created by…

Quantum Physics · Physics 2009-11-11 P. Walther , K. J. Resch , C. Brukner , A. M. Steinberg , J. -W. Pan , A. Zeilinger

Quantum nonlocality, one of the most important features of quantum mechanics, is normally connected in experiments with the violation of Bell-Clauser-Horne (Bell-CH) inequalities. We propose effective methods for the rearrangement and…

Quantum Physics · Physics 2021-06-08 Chen Qian , Yang-Guang Yang , Cong-Feng Qiao , Qun Wang

Quantum entanglement plays a crucial role in quantum information processing tasks and quantum mechanics, hence quantifying unknown entanglement is a fundamental task. However, this is also challenging, as entanglement cannot be measured by…

Quantum Physics · Physics 2021-04-27 Xiaodie Lin , Zhenyu Chen , Zhaohui Wei